wobbly bridge,rope bridge suggestions,

hi all, I am in the process of making a large playground, and wanted to include a wobbly rope bridge for the kids to walk across. I was thinking about 3 feet wide, and at least 20 feet long . I am trying to work out the way to make it, I was thinking for the steps, possibly 5/4×6 deck board, maybe 2 or 3 mated together for stability, with a little space in between the sets,,

maybe have 2 spans / or rises so it isnt just a straight walk but a little uphill and down hill. attchment to the board steps and post is where I am having a little trouble, if I set posts in the ground set on each end, and a set for the uprise,, do you think chain hooked under the boards and attached to each side will make this sturdy and wobbly at the same time,,,

I also will need to attach handrails for safety so maybe rope or chain to that to provide some structure or function is possible,,

I wouldn’t want to suggest anything. I wouldn’t want to alarm you but I would suggest anyone doing something along these lines make sure that their liability insurance is sufficient for the work and in good order. I’m sure that you have taken this into consideration; however, I have heard of others who had not and it caused them deep regret and financial loss.

There is park I go to with my son, and there is a wobbly bridge there that I like. It’s made out of 4×4 posts (it must be cedar; I don’t think PT is allowed any more in playgrounds) mounted on a chain (not sure what grade) and there is a washer in between each “post”. I don’t remember exactly how the hand rails are set up. The chain is hooked up at the ends to metal posts. I’m not sure this is what you’re looking for but I thought it might help.

I truly wish you well, but I also hope that you have very carefully considered any exposure you may have to liability. I have enough experience on legal matters to know that don’t have to do anything wrong to be on the losing end of a major liability suit.

What if one of the neighbor children is over and gets hurt? It might pay to check with the bureau of standards. Or whatever name they have. Google playground safety regulations. At least if or when you do get sued you can produce them to show you built to their specs. Just being realistic.

-- BobG, Lowell, Arkansas--------My goal in life is to be the kind of person my dog thinks I am! Make more saw dust!!

We’re just setting up to build a rope and plank suspension bridge from a “tree house” (loft on our garden shed) to a low tree fort in a large maple across the yard. The bridge will be fun but on a practical level will help keep the kids out of the garden I’m trying to establish. I’ve done some reading but haven’t found any good, suitable build plans/designs. There are a couple of sites you might find helpful to design your own:

http://www.thetreehouseguide.com/forum/forum.php?req=thread&id=52
– this one has a description of a public suspension bridge built by a local community. Some very good pointers for load bearing, tension and safety – and bonus, a nice set of pictures to show how to attach the planks to the suspension chain and a attractive way to tie the handrails.

http://www.thetreehouseguide.com/bridges.htmThis one doesn’t have plans but has some good pointers for design and safety for different types of suspension bridges as well as taking into consideration what type of bridge suits what ages.

My partner is a engineer so when we get a plan laid out and built (and tested) I’ll post what we’ve come up with.From the safety point of view there are a few items that keep popping up on websites:

- Your anchors and the material the anchors are attached to (4×4 or 6×6 posts; trees; decking) must be able to support the load you expect on the bridge. There will be a great deal of tension/load on these attachment points. You can calculate this – (http://answers.yahoo.com/question/index?qid=20060810124024AAEeIEZ) or (http://www.ehow.com/how_12164343_calculate-effect-point-loads-catenary.html) and buy the appropriate materials. You can reduce the load on individual points by increasing the number of anchors for each cable (i.e. using a screw carabiner to branch one chain into a Y shape). For climbing we use 2 anchor points per rope as the minimal safe requirement for a dynamic load (i.e. falling), 3 anchor points is better. One website suggested 2 sets of posts (one behind the other, outside one shorter) to distribute load or tension cable anchoring in the main post into the ground or a tree.

- Your main “cables” also need to be able to bear the load on the bridge. Heavy aircraft cable or steel chain (galvinized) ideally but I’ve also seen static climbing rope (not dynamic rope) >10mm diameter listed (expensive option). The cable also needs to be taught when you attach it, it will ease on its own over time.

- Hand rails should be between 3-5’ high and the design/spacing of gaps should be determined by the age of the kids using the bridge. If you want nice colours you could pick up a couple of different weight climbing ropes (i.e. 8 – 10mm for main lines and 6mm for the weaving) but white nautical line looks nice (well, at least for the first season).

- It appears the easiest overall construction is 1×6” decking boards bolted (washers & nuts on underside) to 2 galvinized steel chains and anchored into 4×4” or 6×6” posts or a tree.

Make sure to observe safety precautions or even let them wear safety helmet(when they’re crossing the bridge), just in case. The area under the rope bridge should be clear with hazardous materials like stones, pointed objects, etc., so that even if they fall, you minimize the damages. With these measures, you can probably prevent major accidents from happening. BTW, I agree that your kids will think about you as the coolest Dad.

-- "someone has to be wounded for others to be saved, someone has to sacrifice for others to feel happiness, someone has to die so others could live"